Two years ago, Karl Rove caused a stir when he planted a seed that Hillary Clinton might have suffered brain damage from a fall.

My, how things have changed.

Today, Clinton’s brain seems to be working just fine, though it’s less than clear that Donald Trump’s is.

Much has been written about Trump’s narcissism, by which most people mean something beyond the garden-variety “he’s such a narcissist.” Columnist Charles Krauthammer, who is a board-certified psychiatrist, wouldn’t officially diagnose such a thing in print, but in a recent column he described Trump in terms that are recognizable to those familiar with the personality disorder.

But perhaps there’s something more going on with Trump. Charitably, I wonder if he is suffering some degree of dementia. Could his quick-to-anger, unfiltered outbursts be attributable to something akin to what Rove once worried about?

Experts say all people have some narcissistic traits, but what does being a "narcissist" mean? (Victoria Walker/The Washington Post)

I think I’m in a unique position to ask this question because of events visited upon me shortly after and pertaining to Rove’s remarks. Appearing on MSNBC’s “Andrea Mitchell Reports” on May 22, 2014, I was asked about those remarks, which I characterized as unfair and premature. I mentioned that I’d once suffered a concussion and that, though serious, symptoms aren’t necessarily persistent over time.

Cue Irony.

Just minutes later, forced by a broken elevator to take the stairs, a slippery step sent me airborne and at the mercy of gravity. The resulting concussion, compounded by my previous one, left me in a vague state for several months.

As it turned out, symptoms can be persistent over time, I quickly learned. Twenty-six months later, I am constantly surprised by incremental improvements after I thought I was well healed months ago.

I recount this history to establish my bona fides in discussing Trump’s often-bizarre and impetuous behavior. Not only did I experience brain damage sufficient to prevent my working for almost a year — irreparably damaging my career and financial stability — but also I’ve studied traumatic brain injury for a book I’m writing.

My own symptoms often mimicked the early stages of Alzheimer’s and dementia. I simultaneously experienced being childlike as well as elderly, variously filled with awe and wonder as well as confused, disoriented, depressed and uncertain.

My particular injury was to the frontal lobe, which governs executive functioning, including decision-making, problem-solving, memory, language, initiative and motivation. Additionally, it regulates inhibition, impulse control, judgment and social behavior. One of the questions neurologists routinely ask friends and family of brain-injured people is whether they’re quicker to anger. In my case, oddly, everyone said, “Oh, no, she’s much nicer!” (This has passed.)

Also, oddly, while I was unable to think of words — calling an umbrella an elephant and saying that my closet, though large, “doesn’t have much parking” — I could conduct mathematical calculations in my head seemingly without thinking.

The brain is a mysterious place.

Trump’s seems especially so — unless he is simply displaying signs not of brain injury, necessarily, but of atrophy associated with aging. If so, then this would help explain his impulsiveness, his inappropriate language, his quick temper and a “mean” streak.

Some of Trump’s neighbors in Palm Beach, Fla., have told me that the man they’re seeing on the stump isn’t the man they’ve known. Although he always has been boastful and consumed with greed and self-promotion, he’s hardly alone in these categories.

What is unique, at least among presidential candidates, is his utter lack of social skills in saying things that would get a schoolchild sent to the principal and very likely to a psychologist. The inhibitory filters that keep most of us from saying whatever pops into our head seem in Trump’s case to be on the blink.

Painful as it is to admit, I too displayed some of this same behavior in the first several months after my fall. Ordinarily polite, I was suddenly prone to interruptions and would blurt out things that never would have left the lips of my previous self. Temperamentally reserved, I became almost aggressive in telling anyone everything. Who was this person?

The thing is, as I read somewhere, when your brain is damaged, your brain is damaged. And while the marketing/branding portion of Trump’s 70-year-old brain seems to be as finely tuned as ever, his general behavior of insults, diatribes and distortions suggests that some key neurons may have left Trump’s tower.

These observations, offered without malice, are made necessary by the fact that Trump is to be provided classified information and by the possibility that he could become president of the United States.